Roxy's CD, compared to the US it does seem that food over here is much more expensive than it is there for some reason.
I only pay for Tango's food, and I just switched her to California Natural Herring & Sweet Patato. It costs me about $60.00 for one 36lb bag, and it'll probably last her about a month and a half or maybe 2 months. She also gets California Natural canned food (both lamb & rice, & chicken & rice) which cost about $2.50/can and she goes through about 8-10 cans a month depending on how much a give her at each meal. So, all together it costs me about $110.00 to feed her each month. Less, during the months that I don't have to buy the kibble obviously. As far as treats go, I buy cookies in bulk and it costs me about $1.30 for a pound and those are for all four dogs. I don't really care as much about the nutritional value of cookies as I do kibble, because its just a treat that they get occasionally. Most of the time they get carrots or a qurter of an apple for a treat.
My mom spends about $45.00 for a 44lb bag of Nutro Natural Choice Chicken meal, rice & oatmeal formula twice a month for the other three dogs and about $2.10/can of Natural Balance and she gets about 10 of those monthly. So all together, thats about $111.00 a month.
I didn't include tax in any of those though, so its actually more.